Cross-linked epoxy resins are polymeric networks used extensively in a variety of applications such as adhesives and coatings. An epoxy network is formed through the mechanism of cross-linking two different moieties, an epoxy matrix and a hardener that causes cross-links to form in the matrix. Chemical reactions that take place between these two moieties create a strong network and significantly alter physical properties of the epoxy matrix. A variety of hardeners (cross-linkers) and additives can be used to further modify the properties of the epoxy upon curing.
In general, epoxy materials are most widely used for the protection of steel against corrosion. Epoxy materials have superior barrier properties and a high degree of adhesive strength that renders them extremely corrosion-resistant. However, the permeability of epoxy materials to water, oxygen, and electrolytes affects the performance of the epoxy coating, resulting in the deterioration of the coating and the subsequent corrosion of the underlying steel. Moisture resistance can be introduced into the epoxy matrix in a number of ways, with hydrophobicity enhancement being by far the most common method. Conventional techniques involve the incorporation of hydrophobic additives to the polymer matrix in order to enhance the overall hydrophobicity of the epoxy resin. Although this method has been reported to be very effective with respect to increasing the overall hydrophobicity of the materials, some non-homogeneity is still introduced into the matrix due to the discrepancies between the additive and the epoxy matrix.
What is therefore needed is an epoxy resin composition that has enhanced hydrophobicity, is homogeneous, and has suitable thermal resistance and stability.